Semiconductors Research Group
The group leader: Associate Professor Maksym Myronov
http://warwick.ac.uk/silicon
Our vision is to create and research advanced semiconductor materials and devices down to nanoscale in order to discover new science and invent new technologies.
We mainly focus on epitaxial growth of the group-IV and related semiconductors epitaxial materials, including thin films, 3D and low-dimensional structures (2D, 1D and 0D), and on understanding their unique material’s properties. Also, we create semiconductor devices at micrometre and nanometre scales. In depth understanding of the materials and devices properties provides essential inputs into research and development of emerging electronic, spintronic, optoelectronic, photonic, photovoltaic, thermoelectric, quantum, MEMS, sensor, energy storage and other semiconductor devices.
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Semiconductors have had a monumental impact on our society. Semiconductor materials are the foundation of modern electronics including radio, computers, phones, and many other gadgets and devices. Anything that is computerized or uses radio waves contains semiconductor devices. |
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Nowadays, most semiconductor devices are fabricated of or on Silicon. Because it is cheap material with superior properties, easy to process and multifunctional. |
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The semiconductor industry is one of the largest industry in the World. It has grown to be a $555 billion industry in 2021. |
Research activities
Novel group IV semiconductor epitaxial structures created of Silicon (Si), Germanium (Ge), Carbon (C) or Tin (Sn) on a Si or Silicon on Insulator (SOI) substrates are a natural evolution in improvement of properties of modern state of the art Si devices and expanding their existing functionalities. They underpin application of these materials with new or enhanced properties in electronic, photonic, photovoltaic, thermoelectric, spintronic, quantum, MEMS, sensor, energy storage and many other devices.
When one or more dimensions of a solid material are reduced to nanometre scale, then some of its properties changes dramatically. With reduction in size, novel electrical, mechanical, chemical, magnetic, and optical properties can be introduced. The resulting structure is then called a low-dimensional structure or a system. Low-dimensional structures are usually classified according to the number of reduced dimensions they have. More precisely, the dimensionality refers to the number of degrees of freedom in the particle momentum. Accordingly, depending on the dimensionality, there are 3D, 2D, 1D and 0D structures.
The confinement of particles, usually electrons, holes or photons, to a low-dimensional structure leads to a dramatic change in their behaviour and to the manifestation of size effects that usually fall into the category of quantum-size effects. As a spatial dimension approaches the atomic scale, a transition occurs from the classical laws to the quantum-mechanical laws of physics. Phenomena that occur on the atomic or subatomic scale cannot be explained outside the framework of quantum-mechanical laws.
The low-dimensional materials exhibit new properties not shown by the corresponding large-scale structures of the same composition. Nanostructures constitute a bridge between molecules and bulk materials. Suitable control of the properties and responses of nanostructures lead to new devices and technologies.
Low-dimensional structures including semiconductor quantum wells (2D), quantum wires (1D) and quantum dots (0D) are gown using epitaxy.
Epitaxy is a process of growing a crystal of a particular orientation on top of another crystal, where the orientation is determined by the underlying crystal. The over layer is called an epitaxial film or epitaxial layer. It is a form of atomic engineering or nanotechnology. The layers are grown onto a crystal polished substrate or wafer and the finished product containing the wafer and its atomically modified surface is known as an epiwafer. It is the number of layers, their atomic composition and the order in which they are grown that determines the precise physical, electronic and optical properties of the material. Quality, performance and lifetime of these devices are determined by the purity, structural perfection and homogeneity of the epitaxial layers.
Epitaxial growth is one of the most important techniques to fabricate various state of the art devices. Modern devices require very sophisticated structure, which are composed of thin layers with various compositions. Epitaxy on Si is enabling core technology for most of modern electronic wonders and for many future discoveries.
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Advanced epitaxial growth techniques, such as chemical vapour deposition (CVD) and molecular beam epitaxy (MBE), enable control of the group IV semiconductor epilayers thickness down to a monolayer accuracy. They include Solid Source MBE (SS-MBE), Gas Source MBE (GS-MBE), Ultra High Vacuum CVD (UHV-CVD), Low Pressure CVD (LP-CVD), Plasma Enhanced CVD (PE-CVD) and Reduced Pressure CVD (RP-CVD).
Among these techniques, the SS-MBE is know as an ultimate research one due to its flexibility and RP-CVD as an ultimate industrial technique due to reliability, reproducibility and unprecedented wafer scalability. RP-CVD is routinely used by leading companies in the semiconductor industry to grow epitaxial layers on Si wafers of up to 300 mm diameter. The Si wafers up to 450 mm diameter are commercially available.
Research highlights
References
Outreach
Breakthrough in enhancement of hole mobility in strained germanium leads to emergence of new class of quantum materials
2D holes reveal first fractional quantization
Student's opportunities
We created a stimulating working environment to attract outstanding students and help them establish their own creative skills. Training and learning through research is an effective way to prepare a student for industrial or academic careers. Our research programs offer students an opportunity to undertake world-class and multidisciplinary research; to use well established or innovative approaches and state of the art experimental equipment and techniques; and to interact with researchers, scientists and engineers with diverse backgrounds. This helps them gain a diversified training and enrich their interpersonal skills, which are highly needed and essential in an increasingly global and multicultural scientific research.